My Carrier high efficiency furnace

hvac5646 · 02-24-2012, 08:00 AM

goodluck.

wxia · 02-24-2012, 10:10 AM

mrwkndr: It looks that you have the exactly the same problem as mine. Let me know how your problem is solved if it is solved.

I looked at my furnace and there is no ease way to open it from the sides (in order to look into the heat exchanger). There are other things in the way.

wxia · 03-06-2012, 02:20 PM

My furnace problem may be temperature sensitive. For the past week, it has not been a problem probably due to a little warmer temperature in my furnace room as our outside temperature has risen to generally above freezing (I am in Salt Lake City, Utah). My furnace (downstairs) does not need to run at night. Does this mean some component of the board or switch locks up at low temperatures but can be re-activiated with a power surge from the flip of the on/off switch?

how · 03-06-2012, 02:59 PM

All borderline parts can be affected by the difference that outside temp presents because it makes the furnace run more often and for longer.

It probably means though that you might be able to instigate a lockout while testing components by turning up the thermostat high enough to mimic the over night colder conditions.

If you can instigate a lock out on your schedule, then you can at least test out one component per lockout..

wxia · 03-07-2012, 06:32 PM

how: Your sugestion is plausible but I doubt it is that simple. In my most recent furnace "lockouts," the temperatures on my first floor were around 62 degrees which was 6 degrees below what the thermostat called for. I do not remeber that the furnace was ever running shortly before I noticed the "lockout." The furnace is located in the basement which would probably be 10 degrees colder than the thermostat's location. That 62 degrees was probably the lowest temperature reached without the furnace heating at night on my first floor (rather than the furnace ran too long before it quit or was locked out). Recently, under a little warmer climate conditions, the furnace have had no problems heating my first floor to 68 degrees and maintaining it at that temperature all day.

how · 03-07-2012, 07:47 PM

Who knows???
People seldom notice an intermitant lockout until they get chilly... which is some time after the furnace locked out and is dependant on how well your home holds in the heat.

If you crank up your heat up 5 degrees above what is normal for you and the furnaces locks out after a while then you have gained an active method for testing components for what was formally a difficult to diagnose intermitant problem.
If the furnace doesn't lock out..then its just onto the next idea.

**beenthere** · 03-07-2012, 08:51 PM

Restricting condensate drain.

wxia · 03-09-2012, 02:47 PM

Yesterday I cranked up my thermostat by 5 degrees more. The furnace ran for more than two hours with no problems - no lockout!

I looked at the condensate drain and did not see anything abnormal. There is evidence the condensate did drain, although I do not know how much. I am not sure how to tell if the drain is restricted.

**beenthere** · 03-09-2012, 03:21 PM

Remove trap and wash it out. Also blow out drain line.

wxia · 03-09-2012, 08:33 PM

I removed the hoses from the top of the condensate trap and blew air thru the trap and the hoses separately (with my mouth). There was no restriction.

**beenthere** · 03-09-2012, 08:39 PM

I wash the traps out with dish soap. Lots of dirt in them. may not be your problem.

wxia · 02-06-2013, 09:41 PM

It was the batteries that were low in the thermostat. Once I replaced them it has no more problems. This explains why I had problems often in the cold mornings.